WO2013031844A1

WO2013031844A1 - Liquid ink

Info

Publication number: WO2013031844A1
Application number: PCT/JP2012/071864
Authority: WO
Inventors: 竹内　一雅
Original assignee: 日立化成株式会社
Priority date: 2011-08-30
Filing date: 2012-08-29
Publication date: 2013-03-07
Also published as: JP6007910B2; JPWO2013031844A1; TWI606096B; CN103781860A; KR20140068946A; CN103781860B; KR102036135B1; TW201319180A

Abstract

Provided is a liquid ink containing: a thermosetting resin composition comprising an organic polymer, a thermosetting resin, and an inorganic filler; and a solvent for dissolving or dispersing the thermosetting resin composition. When the thermosetting resin composition is cured, there is formed a cured product (1) having a storage elastic modulus at 25°C of 500 MPa or lower, and a tensile elastic modulus of 0.5 to 3.0 GPa.

Description

Liquid ink

The present invention relates to a liquid ink.

Conventionally, various printed wiring boards of single side, double side or multilayer have been widely used in the field of industrial equipment or consumer equipment. In electronic devices, only one printed wiring board is rarely used. For example, a plurality of printed wiring boards divided by function are generally used. Usually, a plurality of wiring boards are connected by various connectors.

Electronic devices are aimed at lightness, thinness and smallness, and high-density mounting printed wiring boards representing lightness, thinness and shortness are especially incorporated in recent mobile phones, video cameras, and notebook computers. In these electronic devices, it is necessary to incorporate a plurality of printed wiring boards in a limited space in a compact manner. However, if the wiring boards are connected to each other by a connector, the connection becomes difficult. For this reason, various so-called flexible-rigid wiring boards in which a flexible substrate such as a polyimide film substrate and a rigid substrate are combined have been proposed.

For example, a method for manufacturing a rigid flexible wiring board has been proposed in which a rigid substrate and a flexible substrate are thermocompression bonded via an adhesive sheet, and a circuit of the rigid substrate and the flexible substrate is electrically connected through a through hole (for example, (See Patent Document 1).

Further, by laminating a rigid substrate that does not have flexibility on a flexible substrate that has flexibility, and partially providing a window space in the rigid substrate to expose the flexible substrate, flexibility is partially provided. There has been proposed a method for manufacturing a rigid flexible substrate (see, for example, Patent Document 2).

Furthermore, it has been proposed to provide rigid properties partially by increasing the thickness of the conductor portion of the printed wiring board (see, for example, Patent Document 3).

JP-A-2-39594 Japanese Patent Laid-Open No. 5-90756 JP 2006-352103 A

The main object of the present invention is to increase the rigidity of any part that does not require flexibility while maintaining good bendability for a flexible substrate such as a flexible printed wiring board. It is to provide a liquid ink.

The present invention relates to a liquid ink containing a thermosetting resin composition containing an organic polymer, a thermosetting resin and an inorganic filler, and a solvent for dissolving or dispersing the thermosetting resin composition. When the thermosetting resin composition is cured, a cured product having a storage elastic modulus at 25 ° C. of 500 MPa or less and a tensile elastic modulus of 0.5 GPa to 3.0 GPa can be formed.

According to the liquid ink according to the present invention, since the cured product of the thermosetting resin composition to which the inorganic filler is added has the specific storage elastic modulus and tensile elastic modulus, the flexible printed wiring board. The rigidity of an arbitrary portion that does not require flexibility can be increased while maintaining good bendability with respect to a substrate having flexibility such as the above.

The thermosetting resin composition may contain 50% by mass or more of an inorganic filler based on the total solid content of the thermosetting resin composition (components other than the solvent in the liquid ink). The organic polymer may contain an acrylic resin. Thereby, the thermosetting resin which forms the hardened | cured material which has said specific storage elastic modulus and tensile elastic modulus is comprised especially easily.

The acrylic resin may have a glycidyl group. The weight average molecular weight of the acrylic resin may be 400,000 to 1.8 million, 500,000 to 1.5 million, or 800,000 to 1.4 million.

The inorganic filler may contain silica particles. The silica particles may be surface-treated with a silane coupling agent. Thereby, sedimentation of silica particles is suppressed and a more stable liquid ink can be obtained. From the same viewpoint, the silane coupling agent may have an amino group.

The thermosetting resin may contain an epoxy resin. In this case, the thermosetting resin composition may further contain a phenol resin.

The epoxy resin may contain a biphenyl aralkyl type epoxy resin. Since the biphenyl aralkyl type epoxy resin is highly compatible with an organic polymer such as an acrylic resin, a liquid ink excellent in dispersion stability can be obtained by using the biphenyl aralkyl type epoxy resin.

The liquid ink according to the present invention can be used for applying a liquid ink to a polyimide film substrate and curing the applied liquid ink to form a cured film that increases the rigidity of the polyimide film substrate.

In addition, the liquid ink according to the present invention may be used to form a cured film that increases the rigidity of the flexible printed wiring board by applying the liquid ink to the flexible printed wiring board and curing the applied liquid ink. it can.

According to the present invention, a liquid ink that can increase the rigidity of an arbitrary portion that does not require flexibility while maintaining good bendability for a flexible substrate such as a flexible printed wiring board. Is provided.

The cured film formed with the liquid ink according to the present invention exhibits good adhesion to the polyimide film. Therefore, by forming a cured film by applying liquid ink to a portion of the flexible printed wiring board that has a polyimide film substrate as a substrate and does not require flexibility, a cured film is formed while avoiding a decrease in reflow resistance. It is possible to increase the rigidity of the flexible wiring board in the portion thus formed and to provide rigidity. That is, a rigid-flexible printed wiring board having a rigid portion and a flexible portion can be manufactured by a simple process. Such a rigid-flexible printed wiring board can contribute to weight reduction of various electronic devices.

Furthermore, since the cured film formed with the liquid ink according to the present invention has high reflow resistance, the high level of reflow resistance required when using lead-free solder is easily achieved. Achieved.

It is sectional drawing which shows one Embodiment of the state in which the cured film was provided in contact with the base material. FIG. 6 is a stress-displacement curve and a tangent line of a cured product of the liquid ink obtained in Example 11. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

FIG. 1 is a cross-sectional view showing an embodiment in which a cured film 1 is provided in contact with a base material 10. The base material 10 is a flexible base material having flexibility such as a polyimide film. The rigidity of the base material 10 is increased in the portion in contact with the cured film 1 as compared with the case where the cured film 1 is not formed. In other words, the self-supporting property of the base material 10 is enhanced in the portion in contact with the cured film 1. When the substrate 10 is a flexible printed wiring board, the portion of the substrate 10 in contact with the cured film 1 can function as a rigid portion of a rigid-flexible wiring board, for example.

The liquid ink according to this embodiment can be used to form the cured film 1. For example, the cured film 1 is formed by applying liquid ink to the substrate 10 and curing the applied liquid ink. The thickness of the cured film 1 is 50 to 300 μm, 80 to 200 μm, or 100 to 150 μm.

The liquid ink according to the present embodiment contains a thermosetting resin composition containing an organic polymer that is a polymer material, a thermosetting resin, and an inorganic filler, and a solvent that dissolves or disperses the thermosetting resin composition. .

When the thermosetting resin composition in the liquid ink is cured by heating, for example, a cured product having a storage elastic modulus at 25 ° C. of 500 MPa or less and a tensile elastic modulus of 0.5 GPa to 3.0 GPa (for example, A cured film 1) is formed.

The storage elastic modulus at 25 ° C. of the cured product is measured by measuring the dynamic viscoelasticity of the film-like cured product. More specifically, the storage elastic modulus at 25 ° C. of the cured product is the dynamic viscoelasticity of a film-like cured product having a width of 5 mm and a length of 30 mm, a tensile mode, a distance between chucks of 20 mm, a period of 10 Hz, and a rate of temperature increase. It can obtain | require by the method of reading the storage elastic modulus in 25 degreeC from the viscoelasticity curve showing the relationship between the storage elastic modulus and temperature obtained by measuring on conditions of 5 degreeC / min. The cured product as the measurement sample is formed, for example, by drying a liquid ink film having a thickness of 125 μm by heating at 110 ° C. for 10 minutes and then curing by heating at 185 ° C. for 30 minutes.

The tensile modulus is the maximum value of the tangential slope of the stress-displacement curve (elastically deformed part) obtained when a strip-shaped cured product is prepared as a measurement sample and tensile stress is applied to it at a pulling speed of 50 mm / min. Is the initial elastic modulus obtained from The tensile test is usually performed in an atmosphere of about 23 ° C.

The tensile elastic modulus of the cured product of the thermosetting resin composition according to the present embodiment mainly varies depending on the content of the inorganic filler having a high elastic modulus. In a thermosetting resin composition containing an organic polymer, a thermosetting resin, and an inorganic filler, if the content of the inorganic filler is 50% by mass or more based on the mass of the thermosetting resin composition, 0.5 GPa to There is a high possibility that a cured product having a tensile elastic modulus of 3.0 GPa is formed. When the tensile elastic modulus of the cured product of liquid ink is in the range of 0.5 GPa to 3.0 GPa, cracks are hardly generated in the cured film when the substrate is bent together with the cured film. That is, the cured film 1 can be formed while maintaining the high flexibility of the substrate 10. From the same viewpoint, the tensile modulus of the cured product of the liquid ink material may be 0.7 GPa to 2.0 GPa.

On the other hand, the storage elastic modulus of the cured product of the thermosetting resin composition according to the present embodiment is not affected by the inorganic filler so much as the tensile elastic modulus, and the comparison mainly reflects the low elastic modulus of the resin component. Is maintained at a low value. Specifically, the storage elastic modulus at 25 ° C. of the cured product may be 500 MPa or less, or 120 MPa or less. Particularly excellent bending property and reflow resistance are achieved by the low storage elastic modulus of the cured product. The lower limit of the storage elastic modulus is usually about 10 MPa and may be 25 MPa.

A preferred embodiment of a thermosetting resin composition that forms a cured film having the above characteristics will be described in detail below.

As described above, the thermosetting resin composition according to the present embodiment has an inorganic content of 50% by mass or more based on the mass of the total solid content of the thermosetting resin composition (components other than the solvent in the liquid ink). A filler may be included. 70 mass% or more may be sufficient as the content rate of an inorganic filler. The content of the inorganic filler may be 90% by mass or less, or 80% by mass or less from the viewpoint of tensile elastic modulus.

The inorganic filler may be composed of one kind of particle or may be composed of a combination of two or more kinds of particles. The average particle size of the inorganic filler may be 1 to 100 μm, 1 to 50 μm, 1 to 20 μm, or 1.5 to 10 μm. The inorganic filler may be a mixture of plural kinds of fillers having different average particle diameters. Thereby, the space filling rate by an inorganic filler can be raised.

The inorganic filler may be silica particles. The silica particles may be, for example, spherical silica obtained by a sol-gel method, crushed silica refined by pulverization, dry silica, or wet silica.

Commercially available products of spherical silica include MSR-2212, MSR-SC3, MSR-SC4, MSR-3512, MSR-FC208 (above, trade name manufactured by Tatsumori Co., Ltd.), Excelica (trade name manufactured by Tokuyama Corporation), SO -E1, SO-E2, SO-E3, SO-E5, SO-E6, SO-C1, SO-C2, SO-C3, SO-C5, SO-C6 (above, product names manufactured by Admatechs Co., Ltd.) Etc. Commercially available products of crushed silica include Crystallite 3K-S, NX-7, MCC-4, CMC-12, A1, AA, CMC-1, VX-S2, VX-SR (above, manufactured by Tatsumori Co., Ltd.) Name), F05, F05-30, F05-12 (above, product names manufactured by Fukushima Ceramics Co., Ltd.), and the like. Dry silica such as Leolo Seal, and wet silica such as Toku Seal and Fine Seal (trade name, manufactured by Tokuyama Corporation) can also be used.

Silica particles may be surface-treated with a silane coupling agent. Thereby, sedimentation of silica particles is suppressed and a liquid ink with higher dispersion stability can be obtained.

Examples of the silane coupling agent as a surface treating agent used for surface treating silica particles include vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3- Glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3 Acryloxypropyltrimethoxysilane, n-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, triethoxysilane, n-2- (aminoethyl) -3-aminopropyltrimethoxysilane, n-2- (amino Ethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl -3-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3- Mercaptopropyltrimethoxy Selected from the group consisting of lanthanum, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane, polycondensate of dimethylsilane, polycondensate of diphenylsilane, and copolycondensate of dimethylsilane and diphenylsilane It is. Among these, a silane coupling agent having an amino group can be selected.

The organic polymer constituting the thermosetting resin composition may be an acrylic resin or a polyamide-imide resin from the viewpoints of adhesion to the polyimide film substrate and heat resistance.

The polyamide-imide resin may have a siloxane group and / or an aliphatic group in addition to the amide group and the imide group. The weight average molecular weight of the polyamideimide resin may be 10,000 to 150,000, 30,000 to 100,000, or 50,000 to 80,000. In this specification, a weight average molecular weight is a standard polystyrene conversion value calculated | required by GPC measurement.

The acrylic resin is generally a copolymer composed of a polymerizable monomer containing two or more kinds of acrylic monomers. Acrylic resins can be combined in a wide range by combining various commercially available acrylic monomers, and can be manufactured at low cost. In addition, the acrylic resin is excellent in that the printed liquid ink can be easily dried because it has good solubility in a low-boiling ketone solvent.

The acrylic monomer constituting the acrylic resin is not particularly limited. For example, acrylonitrile, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, T-butyl acrylate, pentyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, dodecyl acrylate, octadecyl acrylate, butoxyethyl acrylate, phenyl acrylate, benzyl acrylate, acrylic Naphthyl acrylate, cyclohexyl acrylate, isobornyl acrylate, norbornyl methyl acrylate, tricycloacrylate [5.2.1. O ^2,6 ] dec-8-yl (dicyclopentanyl acrylate), tricycloacrylate [5.2.1. ^O2,6 ] dec-4-methyl, adamantyl acrylate, isobornyl acrylate, norbornyl acrylate, tricyclohexyl acrylate [5.2.1. ^O2,6 ] dec-8-yl, tricyclohexyl acrylate [5.2.1. Acrylic acid esters such as O ^2,6 ] dec-4-methyl and adamantyl acrylate, and ethyl methacrylate (ethyl methacrylate), n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate (butyl) Methacrylate), i-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, butoxyethyl methacrylate, Phenyl methacrylate and naphthyl methacrylate such as cyclopentyl methacrylate, cyclohexyl methacrylate, methyl cyclohexyl methacrylate, tricyclohexyl methacrylate, norbornyl methacrylate, methacrylate Acid norbornylmethyl, isobornyl methacrylate, bornyl methacrylate, menthyl, adamantyl methacrylate, tricyclo [5.2.1. ^O2,6 ] dec-8-yl (dicyclopentanyl methacrylate) and tricyclomethacrylate [5.2.1. One or two or more monomers selected from methacrylic acid esters such as O ^2,6 ] deca 4-methyl.

From the point of heat resistance and adhesiveness of the cured film formed from liquid ink, the acrylic monomer constituting the acrylic resin is from the group consisting of carboxyl group, hydroxyl group, acid anhydride group, amino group, amide group and epoxy group. It may contain a functional group-containing monomer having at least one selected functional group and at least one (meth) acryl group. Examples of the functional group-containing monomer include carboxyl group-containing monomers such as acrylic acid, methacrylic acid and itaconic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, methacrylic acid Hydroxyl group-containing monomers such as 2-hydroxypropyl, N-methylolmethacrylamide and (o-, m-, p-) hydroxystyrene, acid anhydride group-containing monomers such as maleic anhydride, diethylaminoethyl acrylate and diethylamino methacrylate Amino group-containing monomers such as ethyl, glycidyl acrylate, glycidyl methacrylate (glycidyl methacrylate), glycidyl α-ethyl acrylate, glycidyl α-n-propyl acrylate, 3,4-epoxybutyl acrylate Methacrylic acid 3,4-epoxybutyl, acrylic acid-4,5-epoxypentyl, acrylic acid-6,7-epoxyheptyl, methacrylic acid-6,7-epoxyheptyl, acrylic acid-3-methyl-4- Epoxybutyl, 3-methyl-3,4-epoxybutyl methacrylate, 4-methyl-4,5-epoxypentyl acrylate, 4-methyl-4,5-epoxypentyl methacrylate, 5-acrylic acid-5 Methyl-5,6-epoxyhexyl, acrylic acid-β-methylglycidyl, methacrylic acid-β-methylglycidyl, α-ethylacrylic acid-β-methylglycidyl, acrylic acid-3-methyl-3,4-epoxybutyl, 3-methyl-3,4-epoxybutyl methacrylate, 4-methyl-4,5-epoxypentyl acrylate, meta Consists of epoxy group-containing monomers such as 4-methyl-4,5-epoxypentyl acrylate, 5-methyl acrylate, 6-epoxyhexyl acrylate and 5-methyl-5,6-epoxyhexyl methacrylate Selected from the group. These are used alone or in combination of two or more.

The acrylic resin may further contain another monomer copolymerized with the acrylic monomer. Other monomers include, for example, 4-vinylpyridine, 2-vinylpyridine, α-methylstyrene, α-ethylstyrene, α-fluorostyrene, α-chlorostyrene, α-bromostyrene, fluorostyrene, chlorostyrene, bromostyrene Aromatic vinyl compounds such as methylstyrene, methoxystyrene and styrene, and N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, Ni-propylmaleimide, N-butylmaleimide, Ni-butylmaleimide , Nt-butylmaleimide, N-laurylmaleimide, N-cyclohexylmaleimide, N-benzylmaleimide, N-phenylmaleimide and the like, and at least one compound selected from the group consisting of N-substituted maleimides.

The acrylic resin may have a glycidyl group, particularly when the thermosetting resin is an epoxy resin. When the acrylic resin has a glycidyl group, the heat resistance of the cured film is further improved. Therefore, the acrylic resin may contain glycidyl methacrylate or glycidyl acrylate, which is a functional group-containing monomer, as a monomer unit. Based on the amount of all polymerizable monomers constituting the acrylic resin, the content of glycidyl methacrylate may be 0.5 to 10% by mass, 1 to 8% by mass, or 2 to 5% by mass.

The acrylic resin may contain alkyl acrylate as a monomer from the viewpoint of adhesiveness with a flexible wiring board when a cured film is used. The alkyl group of the alkyl acrylate may have 1 to 12 or 2 to 10 carbon atoms. Based on the amount of all polymerizable monomers constituting the acrylic resin, the content of the alkyl acrylate may be 50 to 99% by mass, 60 to 98% by mass, or 70 to 96% by mass. The alkyl acrylate is selected from, for example, ethyl acrylate and butyl acrylate.

The acrylic resin may contain acrylonitrile or methacrylonitrile as a monomer from the viewpoint of toughness and adhesiveness. Based on the amount of all polymerizable monomers constituting the acrylic resin, the content of acrylonitrile or methacrylonitrile may be 0.5 to 10% by mass, 1 to 8% by mass, or 2 to 5% by mass. Good.

Examples of acrylic resins include copolymers of glycidyl methacrylate and alkyl (meth) acrylate, glycidyl methacrylate, copolymers of alkyl (meth) acrylate and (meth) acrylonitrile, glycidyl methacrylate, alkyl (meth) acrylate and dicyclopentanyl. It is a copolymer of (meth) acrylate.

The weight average molecular weight of the acrylic resin may be 400,000 to 1.8 million, 500,000 to 1.5 million, or 800,000 to 1.4 million. If the weight average molecular weight is less than 400,000, the viscosity of the liquid ink is low, so that the dispersion stability of the inorganic filler may be lowered, or the liquid ink may not be able to exhibit thixotropy. Further, when the weight average molecular weight of the acrylic resin is low, the cured film becomes brittle and the bending property of the cured film tends to be lowered. When the weight average molecular weight of the acrylic resin exceeds 1,800,000, the solubility in a solvent is remarkably lowered, and it tends to be difficult to increase the solid content concentration in the liquid ink. When the concentration of the solid content of the liquid ink is low, it is necessary to consider the control of the film thickness of the applied liquid ink and the reduction of the film due to drying shrinkage.

The glass transition temperature (Tg) of the acrylic resin may be −50 to 100 ° C., −45 to 20 ° C., or −40 ° C. to 5 ° C. When the glass transition temperature of the acrylic resin is within these numerical ranges, the storage elastic modulus and tensile elastic modulus of the cured film can be easily controlled while suppressing stickiness of the cured film. The Tg of the acrylic resin can be measured by DSC (Differential scanning calorimetry), but the Tg of the acrylic resin composed of n types of monomers can also be calculated by the following calculation formula (FOX formula).
Tg (° C.) = {1 / (W ₁ / Tg ₁ + W ₂ / Tg ₂ +... + W _i / Tg _i +... + W _n / Tg _n )}-273
In the FOX equation, _Tg i (K) shows a glass transition temperature of the homopolymer of each monomer, _{W i} represents the weight fraction of each _{_{monomer, W 1 + W 2 + ...}} + W i + ... W n = 1.

For example, the glass transition temperature (Tg) of an acrylic resin obtained by copolymerization at a ratio of 5% by mass of glycidyl methacrylate, 5% by mass of acrylonitrile, 85% by mass of ethyl acrylate, and 5% by mass of butyl acrylate is as follows: Is calculated.
Tg = {1 / (0.05 / 319 + 0.05 / 498 + 0.85 / 251 + 0.05 / 219)}-273 = −14.7 ° C.

The thermosetting resin constituting the thermosetting resin composition is a compound having a curable functional group (for example, an epoxy group). The thermosetting resin is, for example, one or more selected from epoxy resins, polyimide resins, polyamideimide resins, triazine resins, phenol resins, melamine resins, polyester resins, cyanate ester resins, and modified systems of these resins. .

The thermosetting resin may contain a high molecular weight component for the purpose of improving the flexibility and heat resistance of the cured film. However, the molecular weight of the thermosetting resin is usually 3000 or less.

The epoxy resin is, for example, a polyglycidyl ether obtained by reacting a polyhydric alcohol such as bisphenol A, a novolac-type phenol resin, and an ortho-cresol novolac-type phenol resin or a polyhydric alcohol such as 1,4-butanediol with epichlorohydrin. Polyglycidyl esters obtained by reacting polybasic acids such as phthalic acid and hexahydrophthalic acid with epichlorohydrin, N-glycidyl derivatives of compounds having amino groups, amide groups or heterocyclic nitrogen bases, and alicyclic rings It is 1 type, or 2 or more types chosen from a formula epoxy resin. Among these, polyglycidyl ethers selected from biphenyl aralkyl type epoxy resins and naphthalene type tetrafunctional epoxy resins, and N-glycidyl derivatives of compounds having an amide group or a heterocyclic nitrogen base are organic polymers (particularly acrylics). Resin).

Examples of the phenol resin include phenol type, bisphenol A type, cresol novolac type, and aminotriazine novolac type phenol resins. From the point of compatibility with the acrylic resin, one or both of the cresol novolak type and aminotriazine novolak type phenol resins can be selected. The amine triazine novolac type phenol resin has a structural unit represented by the following structural formula (I). When combined with an epoxy resin, the phenolic resin may function as a curing agent for the epoxy resin.

[In the formula (I), R represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 30. ]

The thermosetting resin composition may contain a curing agent usually used for curing the thermosetting resin. For example, when the thermosetting resin is an epoxy resin, the curing agent is selected from dicyandiamide, diaminodiphenylmethane, diaminodiphenylsulfone, phthalic anhydride, pyromellitic anhydride, and polyfunctional phenols such as phenol novolac and cresol novolac. be able to.

Often, an accelerator is used for the purpose of promoting the reaction between the thermosetting resin and the curing agent. The kind and compounding quantity of an accelerator are not specifically limited. For example, an imidazole compound, an organic phosphorus compound, a tertiary amine, or a quaternary ammonium salt is used, and two or more kinds may be used in combination.

Total mass of organic polymer (acrylic resin, etc.), thermosetting resin (epoxy resin, etc.) and curing agent (phenolic resin, etc.) (may correspond to the total mass of components other than inorganic filler of thermosetting resin composition) )), The organic polymer content may be 40-90% by weight, 50-85% by weight, or 60-80% by weight. The total of the glycidyl group of the acrylic resin and the epoxy group of the epoxy resin and the amount of hydroxyl group of the phenol resin may be substantially equivalent. The ratio between the thermosetting resin and the curing agent is appropriately set within a range usually employed in consideration of their reactivity and the like.

As the solvent constituting the liquid ink, for example, ketone solvents such as methyl ethyl ketone and cyclohexanone can be used. From the viewpoint of printability, cyclohexanone can be selected. The concentration of the thermosetting resin composition (components other than the solvent) in the liquid ink may be 40 to 70% by mass based on the mass of the liquid ink.

The liquid ink can be prepared by mixing each component constituting the thermosetting resin composition and a solvent, and stirring if necessary. The inorganic filler may be dispersed and slurried in advance in an organic solvent containing a surface treatment agent. The solid content concentration (inorganic filler concentration) of the slurry containing the inorganic filler and the solvent is not particularly limited, but is 50 to 90 mass%, 60 to 80 mass%, or 65 to 75 mass% based on the mass of the slurry. There may be. A mixture of an organic polymer, a thermosetting resin and a curing agent may be prepared in advance. A liquid ink can be obtained by mixing the mixture and the slurry of the inorganic filler.

The liquid ink according to this embodiment is applied to a predetermined portion of the base material in order to form a cured film. The coating method may be continuous coating such as bar coating, comma coating, and roll coating, or may be printing such as screen printing and metal mask printing.

The applied liquid ink (coating film) is cured after drying if necessary. The drying temperature may be 50-150 ° C, 80-130 ° C, or 100-120 ° C. A coating film is hardened | cured by processing at high temperature further. The curing temperature may be 150-250 ° C, 160-200 ° C, or 180 ° C-190 ° C.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Example 1
7 g of N-phenyl-3-aminopropyltrimethoxysilane (KBM573, trade name manufactured by Shin-Etsu Silicon Co., Ltd.) as a surface treatment agent is dissolved in 300 g of methyl ethyl ketone, and F05-12 (Fukushima Ceramics), which is crushed silica, is dissolved therein. (Product name) 700 g was added with stirring, and then further stirred at room temperature for 1 hour. A 200-mesh nylon cloth was used to filter the crushed silica agglomerates, and a slurry-like filtrate (silica slurry) was obtained. 350 g of a methyl ethyl ketone (MEK) solution (concentration 20% by mass) of a copolymer of glycidyl methacrylate, ethyl acrylate and butyl acrylate (weight average molecular weight 1,300,000, epoxy equivalent 7800, Tg-45 ° C.), and a biphenyl aralkyl type 34.2 g of MEK solution (concentration 50% by mass) of epoxy resin (NC-3000H, Nippon Kayaku Co., Ltd.) and MEK solution of phenol resin (LA-3018, trade name of Dainippon Ink Co., Ltd.) 25.8 g (concentration 50% by mass) and 0.5 g of 1-cyanoethyl-2-phenylimidazole (2PZ-CN, trade name, manufactured by Shikoku Kasei Co., Ltd.) were mixed and stirred to obtain a resin solution. To this resin solution, 430 g of silica slurry was added and stirred for 1 hour to obtain a liquid ink.

Examples 2 to 11, Reference Examples 1 to 4 and Comparative Examples 5 to 8
Liquid inks were prepared in the same manner as in Example 1 except that the materials shown in Tables 1 and 2 were used in the mixing ratios shown in the tables. The blending ratio of the organic polymer, the thermosetting resin and the curing agent is based on the mass other than the inorganic filler of the thermosetting resin composition, and the blending ratio of the inorganic filler is the total solid of the thermosetting resin composition. This is based on the mass of components (components other than the solvent in the liquid ink).

Example 12
In 300 g of cyclohexanone, 7 g of N-phenyl-3-aminopropyltrimethoxysilane (KBM573, trade name, manufactured by Shin-Etsu Silicon Co., Ltd.) as a surface treatment agent was dissolved, and SO-25R (ADMATEX), which is spherical silica, was dissolved therein. (Product name) 700 g was added with stirring, and then further stirred at room temperature for 1 hour. A 200-mesh nylon cloth was used to filter out the agglomerates of spherical silica to obtain a slurry-like filtrate (silica slurry). 350 g of a cyclohexanone solution (concentration 20% by mass) of a copolymer of glycidyl methacrylate, acrylonitrile, ethyl acrylate and butyl acrylate (weight average molecular weight 450,000, Tg-14.7 ° C.), which is an acrylic resin, and a biphenylaralkyl type epoxy resin ( NC-3000H, Nippon Kayaku Co., Ltd. trade name) cyclohexanone solution (concentration 50 mass%) 34.2 g and phenol resin (LA-3018, Dainippon Ink Co., Ltd. trade name) propylene glycol monomethyl ether solution ( 25.8 g (concentration 50% by mass) and 0.5 g of 1-cyanoethyl-2-phenylimidazole (2PZ-CN, trade name, manufactured by Shikoku Kasei Co., Ltd.) were mixed and stirred to obtain a resin solution. To this resin solution, 430 g of the silica slurry (inorganic filler concentration: 70% by mass) was added and stirred for 1 hour to obtain a liquid ink.

Details of each material shown in Tables 1 and 2 are as follows.
1. Acrylic resin / GMA / EA / BA: Copolymer of glycidyl methacrylate, ethyl acrylate and butyl acrylate (monomer mixing ratio: GMA / EA / BA = 2/26/72 (mass ratio), Tg: −45 ° C.)
GMA / AN / EA / BA: copolymer of glycidyl methacrylate, acrylonitrile, ethyl acrylate and butyl acrylate (monomer mixing ratio: GMA / AN / EA / BA = 5/5/85/5 (mass ratio), Tg : -14.7 ° C)
GMA / EA / BA / FA513AS: Copolymer of glycidyl methacrylate, ethyl acrylate, butyl acrylate and dicyclopentanyl acrylate (monomer mixing ratio: GMA / EA / BA / FA513AS = 5/28 / 38.5 / 28 .5 (mass ratio), Tg: -6.7 ° C)
2. Epoxy resin / NC-3000H: Biphenyl aralkyl type epoxy resin (trade name, manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 290)
EXA4710: Naphthalene type tetrafunctional epoxy resin (Dainippon Ink Co., Ltd. trade name, epoxy equivalent 170)
N770: phenol novolac epoxy resin (Dainippon Ink Co., Ltd., epoxy equivalent 188)
3. Phenolic resin (curing agent)
LA-3018: aminotriazine novolak type phenolic resin (Dainippon Ink Co., Ltd. trade name, hydroxyl group equivalent 151, nitrogen content 18%)
KA-1165: Cresol novolac type phenolic resin (trade name, hydroxyl equivalent 119 manufactured by Dainippon Ink Co., Ltd.)
LA-1356: Aminotriazine novolak type phenolic resin (Dainippon Ink Co., Ltd. trade name, hydroxyl equivalent 146, nitrogen content 19%)
4). Silica particles · F05-12: Crushed silica, product name manufactured by Fukushima Ceramics Co., Ltd. · F05-30: Crushed silica, product name manufactured by Fukushima Ceramics Co., Ltd. · SO-C6 / SO-E3: Spherical silica, products manufactured by Admatex Co., Ltd. Name / SO-25R: Spherical silica, product name manufactured by Admatechs Co., Ltd. Surface treatment agent (silane coupling agent)
・ KBM573: N-phenyl-3-aminopropyltrimethoxysilane, trade name manufactured by Shin-Etsu Silicon Co., Ltd. ・ KBM602: N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, Shin-Etsu Silicon Co., Ltd. Product name: KBM903: 3-aminopropyltrimethoxysilane, Shin-Etsu Silicone Co., Ltd. Product name: KBM5103: 3-acryloxypropyltrimethoxysilane, Shin-Etsu Silicone Co., Ltd .: DMDS / TEMOS: Dimethyl Polysiloxane oligomer formed from dimethoxysilane (DMDS) and tetramethoxysilane (TEMOS)

(Evaluation)
1. Adhesiveness with polyimide film A liquid ink was applied to a polyimide film (Upilex 50S) using a bar coater so that the thickness after drying was 125 μm. The applied liquid ink was dried by heating at 110 ° C. for 10 minutes and then cured by heating at 185 ° C. for 30 minutes to form a cured film that adhered to the polyimide film. The cured film was divided into a grid pattern by 10 notches at intervals of 2 mm and 10 notches at intervals of 2 mm intersecting at right angles with a cutter knife. After sticking an adhesive tape there, it was peeled off and the adhesiveness was evaluated based on the number of grids remaining in the form of a polyimide film. When the number of grids remaining on the polyimide film was large, it was determined that the adhesion with the polyimide was good.

2. Storage elastic modulus of cured product A liquid ink having an amount of 125 μm after drying was applied to a release-treated PET (polyethylene terephthalate) film using a bar coater. The applied liquid ink was dried by heating at 110 ° C. for 10 minutes, and then cured by heating at 185 ° C. for 30 minutes to form a cured film (cured product). A sample having a width of 5 mm and a length of 30 mm was punched from the cured product peeled from the release-treated PET film. This sample was measured for viscoelasticity using a dynamic viscoelasticity measuring device (REOGEL 4000 manufactured by Rheology) at a distance between chucks of 20 mm, a period of 10 Hz, and a temperature rising rate of 5 ° C./min. The storage elastic modulus and Tg at 25 ° C. were determined from the obtained viscoelastic curve.

3. Mechanical property of hardened | cured material The liquid ink of the quantity used as 125 micrometers in thickness after drying was apply | coated to the mold release process PET (polyethylene terephthalate) film using the bar coater. The applied liquid ink was dried by heating at 110 ° C. for 10 minutes, and then cured by heating at 185 ° C. for 30 minutes to form a cured film (cured product). A sample having a width of 10 mm and a length of 100 mm was punched from the cured product peeled from the release-treated PET film. This sample was subjected to a tensile test using an EZ tester at a tensile speed of 50 mm / min to obtain a stress-displacement curve. From the maximum value of the tangential slope of the stress-displacement curve at the initial rise, the tensile elastic modulus was determined according to the following formula. FIG. 2 shows the stress-displacement curve of the cured liquid ink obtained in Example 11. The tensile elastic modulus was calculated from the slope of the tangent line T having the maximum slope among the tangent lines of the stress-displacement curve of FIG.
Tensile modulus (Pa) = maximum value of tangential slope of stress-displacement curve (N / m) × [displacement (m) / cross-sectional area of cured product (m ² )]

4). Self-supporting A liquid ink having a thickness of 125 μm after drying was applied to a polyimide film (Upilex 50S) using a bar coater. The applied liquid ink was dried by heating at 110 ° C. for 10 minutes, and then cured by heating at 185 ° C. for 30 minutes to form a cured film (cured product). The cured film was punched into a size of 10 mm width and 100 mm length together with the polyimide film to obtain a sample. The obtained sample was placed on two platforms installed with an interval of 80 mm so as to span the platforms, and the amount of subsidence at the center of the sample at that time was measured. When the sinking amount was 10 mm or less, it was determined that there was self-supporting property.

5. Bending property A sample composed of a polyimide film and a cured film laminated thereon was applied with a 0.3 mm pin gauge, and the sample was bent to about 180 degrees while being wound around it, and the presence or absence of cracks at that time was observed. A polyimide film was placed outside or inside the pin gauge, and the same evaluation was performed. When the generation of cracks was not recognized, it was determined that the bendability was good.

6). Reflow resistance A sample composed of a polyimide film and a cured film laminated thereon was sandwiched between two metal meshes, and a conveyor type reflow test was performed. That is, the sample was processed three times with a heating profile in which the maximum temperature of the sample surface was 260 ° C. at a speed of 1.2 m / min and the temperature was maintained for 10 seconds. After the treatment, the presence or absence of blistering and peeling between the polyimide film and the cured film was confirmed by visual observation of the appearance. When blistering and peeling were not recognized, it was determined that the reflow resistance was good.

(result)
The liquid inks of the examples had excellent dispersion stability, and no aggregation of silica was observed after standing for 2 weeks. The cured film formed with these liquid inks could give the polyimide film self-supporting properties. Moreover, the adhesiveness with respect to the polyimide of a cured film was also favorable, and there was no problem also in reflow resistance. The liquid ink of Reference Example 1 had a problem in stability because silica aggregated. The liquid inks of Reference Examples 2 and 3 had a problem in stability because the resin separated. The cured film formed with the liquid ink of Comparative Example 5 could not give self-supporting property to the polyimide film. The cured film formed with the liquid ink of Comparative Example 6 could not be folded together with the polyimide film without generating cracks.

The storage elastic modulus at 25 ° C. of the cured product formed from the liquid ink of Reference Example 4 having a composition obtained by removing silica particles from the liquid ink of Example 3 is substantially the same value as the cured product of Example 3. Met. From this, it was confirmed that the storage elastic modulus at 25 ° C. of the cured product is a value mainly reflecting the elastic modulus of the resin component excluding the inorganic filler.

1 ... cured film (cured product), 10 ... substrate.

Claims

A thermosetting resin composition comprising an organic polymer, a thermosetting resin and an inorganic filler, and a solvent for dissolving or dispersing the thermosetting resin composition,
A liquid ink in which when the thermosetting resin composition is cured, a cured product having a storage elastic modulus at 25 ° C. of 500 MPa or less and a tensile elastic modulus of 0.5 GPa to 3.0 GPa is formed.
The liquid ink according to claim 1, wherein the thermosetting resin composition contains 50% by mass or more of the inorganic filler based on the mass of the thermosetting resin composition.
The liquid ink according to claim 1 or 2, wherein the organic polymer contains an acrylic resin.
The liquid ink according to claim 3, wherein the acrylic resin has a glycidyl group.
The liquid ink according to claim 3 or 4, wherein the acrylic resin has a weight average molecular weight of 400,000 to 1,800,000.
The liquid ink according to any one of claims 1 to 5, wherein the inorganic filler contains silica particles.
The liquid ink according to claim 6, wherein the silica particles are surface-treated with a silane coupling agent.
The liquid ink according to claim 7, wherein the silane coupling agent has an amino group.
The liquid ink according to any one of claims 1 to 8, wherein the thermosetting resin contains an epoxy resin, and the thermosetting resin composition further contains a phenol resin.
The liquid ink according to claim 9, wherein the epoxy resin contains a biphenyl aralkyl type epoxy resin.
The liquid film is applied to a polyimide film base material, and the applied liquid ink is cured to form a cured film that increases the rigidity of the polyimide film base material. Liquid ink as described in clause.
The liquid ink is applied to a flexible printed wiring board, and the applied liquid ink is cured to form a cured film that increases the rigidity of the flexible printed wiring board. Liquid ink as described in clause.